lls.c (3300B)
1 /* 2 * linear least squares model 3 * 4 * Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at> 5 * 6 * This file is part of FFmpeg. 7 * 8 * FFmpeg is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU Lesser General Public 10 * License as published by the Free Software Foundation; either 11 * version 2.1 of the License, or (at your option) any later version. 12 * 13 * FFmpeg is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 16 * Lesser General Public License for more details. 17 * 18 * You should have received a copy of the GNU Lesser General Public 19 * License along with FFmpeg; if not, write to the Free Software 20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 21 */ 22 23 /** 24 * @file 25 * linear least squares model 26 */ 27 28 #include <math.h> 29 #include <string.h> 30 31 #include "config.h" 32 #include "attributes.h" 33 #include "float_dsp.h" 34 #include "lls.h" 35 36 static void update_lls(LLSModel *m, const double *var) 37 { 38 int i, j; 39 40 for (i = 0; i <= m->indep_count; i++) { 41 for (j = i; j <= m->indep_count; j++) { 42 m->covariance[i][j] += var[i] * var[j]; 43 } 44 } 45 } 46 47 void avpriv_solve_lls(LLSModel *m, double threshold, unsigned short min_order) 48 { 49 int i, j, k; 50 double (*factor)[MAX_VARS_ALIGN] = (void *) &m->covariance[1][0]; 51 double (*covar) [MAX_VARS_ALIGN] = (void *) &m->covariance[1][1]; 52 double *covar_y = m->covariance[0]; 53 int count = m->indep_count; 54 55 for (i = 0; i < count; i++) { 56 for (j = i; j < count; j++) { 57 double sum = covar[i][j]; 58 59 for (k = 0; k <= i-1; k++) 60 sum -= factor[i][k] * factor[j][k]; 61 62 if (i == j) { 63 if (sum < threshold) 64 sum = 1.0; 65 factor[i][i] = sqrt(sum); 66 } else { 67 factor[j][i] = sum / factor[i][i]; 68 } 69 } 70 } 71 72 for (i = 0; i < count; i++) { 73 double sum = covar_y[i + 1]; 74 75 for (k = 0; k <= i-1; k++) 76 sum -= factor[i][k] * m->coeff[0][k]; 77 78 m->coeff[0][i] = sum / factor[i][i]; 79 } 80 81 for (j = count - 1; j >= min_order; j--) { 82 for (i = j; i >= 0; i--) { 83 double sum = m->coeff[0][i]; 84 85 for (k = i + 1; k <= j; k++) 86 sum -= factor[k][i] * m->coeff[j][k]; 87 88 m->coeff[j][i] = sum / factor[i][i]; 89 } 90 91 m->variance[j] = covar_y[0]; 92 93 for (i = 0; i <= j; i++) { 94 double sum = m->coeff[j][i] * covar[i][i] - 2 * covar_y[i + 1]; 95 96 for (k = 0; k < i; k++) 97 sum += 2 * m->coeff[j][k] * covar[k][i]; 98 99 m->variance[j] += m->coeff[j][i] * sum; 100 } 101 } 102 } 103 104 static double evaluate_lls(LLSModel *m, const double *param, int order) 105 { 106 return ff_scalarproduct_double_c(m->coeff[order], param, order + 1); 107 } 108 109 av_cold void avpriv_init_lls(LLSModel *m, int indep_count) 110 { 111 memset(m, 0, sizeof(LLSModel)); 112 m->indep_count = indep_count; 113 m->update_lls = update_lls; 114 m->evaluate_lls = evaluate_lls; 115 #if ARCH_RISCV 116 ff_init_lls_riscv(m); 117 #elif ARCH_X86 118 ff_init_lls_x86(m); 119 #endif 120 }